


Smells Like a Promise

by mean_whale



Category: Haikyuu!!
Genre: Alpha/Beta/Omega Dynamics, Alpha/Omega, Anal Fingering, Anal Sex, Best Friends, Bottom Iwaizumi Hajime, First Time, Friends to Lovers, M/M, Mating, Mating Bond, Mating Cycles/In Heat, Multiple Orgasms, Omega Iwaizumi Hajime, Omega Verse, Plot What Plot/Porn Without Plot, Scent Marking
Language: English
Status: Completed
Published: 2017-04-03
Updated: 2017-04-03
Packaged: 2018-10-14 12:15:42
Rating: Explicit
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 4,111
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/10536270
Author URL: https://archiveofourown.org/users/mean_whale/pseuds/mean_whale
Summary: Everyone thinks Iwaizumi is a beta, until one day his blockers stop working and he goes to heat in the middle of practise. Who will help him get safely home, and will he have an alpha to spend his heat with?





	

**Author's Note:**

> Written for a request of iwaoi with o!iwa, [71: “I’d kill to be a beta right now.”](http://pornorosso.tumblr.com/post/147364026241/abo-starters-send-one-for-my-muses-reaction)

The day had been completely normal, and Iwaizumi was expecting it to continue normally, when he suddenly felt something change in his body. He froze in the middle of a serve, the volleyball slamming loudly onto the floor, and everyone turned to look at him. Iwaizumi was still staring forward, trying to quickly figure out what the hell was going on in him, when the first alphas started to react. It started as a quiet murmur of pheromones in the gym before the first growl rose from someone’s chest.

Iwaizumi snapped back to reality and looked around. Kyotani was staring at him with such intensity that it made his heart burn, and he tore his eyes away, only to notice how Matsukawa was licking his lips and twitching like he wasn’t sure what commands his brain was giving to his body. Kindaichi had his hands resting on his sides as tight fists, shaking, breathing so heavily that he started to look like he was going to pass out. Kunimi’s bored expression had been replaced by hunger that Iwaizumi would have never thought he’d see, and the young alpha was starting to take a step towards him.

Then there was Oikawa, his hands clasped over his mouth and nose, and Iwaizumi caught the whiff of his pheromones.

Oikawa smelled like lust.

 _Oh_ , Iwaizumi thought to himself.

Oh, indeed. His body was starting to burn, and each alpha was paying close attention to him like he was the most delicious dinner they had ever laid eyes on. Iwaizumi was already feeling how slick accumulated to his hole, but he wasn’t too far gone to feel resentment towards the alphas who were all starting to approach – except for Oikawa, who still seemed to be holding his breath even if it killed him.

The first one to react was a coach, who else, and he turned the alphas’ attention to him, even if for a short moment. That’s when Hanamaki hurried forward, took a hold of Iwaizumi’s elbow, and started urging him out of the gym. When they turned, Iwaizumi heard Kyotani growl low and dangerous, and someone else growl back, but he was ushered out before he could turn to look what was going on behind them.

Hanamaki didn’t stop before they were in the locker room and the door was closed. He released his hold on Iwaizumi and remained by the door, watching his friend sit down on a bench.

“Yeah,” Iwaizumi said, sighed, and rested his head on his hands. “I’m an omega.”

“What happened?” Hanamaki asked.

Iwaizumi turned to look at him. He had been expecting to be asked something else, something like: “How is this even possible?” or “Are you only presenting now?”, not such a sensible question.

“I don’t know,” Iwaizumi said, fear evident in his voice. “The blockers must have stopped working.”

Hanamaki nodded and opened his mouth, but before he could say anything the door was slammed open.

“Iwa-chan!” Oikawa yelled and tried to barge in, but Hanamaki caught him.

“Oikawa!” Hanamaki called, trying to push the alpha out. “You can’t be here! Go away!”

Oikawa wouldn’t listen. He struggled and yelled, and just when footsteps were approaching the room to stop him, he slipped out of Hanamaki’s hold and hurried to Iwaizumi, who had been regarding the fight in disbelief.

“Iwa-chan,” Oikawa breathed, and without a pause pulled the omega into a hug. “You’re okay. You don’t have to be afraid.”

Iwaizumi hardly had any time to process the words before their coaches emerged to the room with the rest of the alphas following. Mizoguchi turned around to angrily tell the alphas to return to the gym, while Irihata approached Oikawa, who was settling onto the bench next to Iwaizumi, still cradling the omega against his chest and stroking his back soothingly.

“Oikawa,” Irihata said with authority that was typical of older alphas. “You can’t stay here.”

Oikawa seemed deaf to the words, continuing to mumble calming words to Iwaizumi. The omega, however, wasn’t listening at all. He was watching how Hanamaki helped Mizoguchi bring the alphas back to their senses and leave, Kyotani still looking just as angry as ever, but Kindaichi blushing all the way to his ears and Matsukawa grinning in apology before briskly walking away. Then Iwaizumi noticed Mizoguchi wince and take a hold of his arm.

“Oikawa bit me,” he heard the coach tell Hanamaki before they both turned back to the scene inside the locker room.

Irihata was still trying to reason with Oikawa, but the young alpha was snuggling his face against Iwaizumi’s neck, whining about something, and Iwaizumi thought that it was as good a time as any to finally focus on what his own body was doing.

He was surprised to realise that the shaking he had felt when he first sat down had subsided, and his muscles were relaxing as he was leaning more into Oikawa’s hold. He turned his head to look at his friend, but only got a face full of soft hair, since Oikawa was still nuzzling his neck.

“Look, everyone else left already,” Mizoguchi tried, clearly agitated. “You need to snap out of it too.”

Oikawa shook his head. Iwaizumi felt like a baby’s favourite toy that the baby didn’t want to surrender to anyone else. He was expecting for it to make him feel bad, but instead he felt more relaxed than he had in ages.

“Hey, Trashykawa,” Iwaizumi barked.

Oikawa immediately lifted his head, eyes going wide as Iwaizumi turned to look at him as best has he possibly could while the alpha was still holding him so close.

“Have you thought this through?” Iwaizumi asked.

Oikawa looked at him, and his heart sped up under the gaze.

“It’s not like you could have made a proper decision,” Iwaizumi added.

Oikawa was staring at him, and he felt his ears start to burn. He glanced to the side and saw that Hanamaki had backed away from the room and was looking elsewhere to give them some semblance of privacy. Mizoguchi, on the other hand, was still looking at the couple on the bench with apprehension, hand clasped over a spot on his arm where Oikawa apparently bit him. Irihata stood still and unrelenting, but had backed away slightly.

“Why didn’t you tell me?” Oikawa asked first with sadness, then: “Did your blockers stop working?”

“You think we have time for that right now?” Iwaizumi asked, irritated by how the heat was making his body burn more and more with each passing second and how Oikawa’s pheromones were slowly starting to cloud his judgement.

Speaking of which, why was he expecting Oikawa to make decisions when he wasn’t sure he had made any of his own yet? He had always pretended to be beta just to make things easier, and the longer he pretended the harder it had been to tell Oikawa the truth, even if he had wanted to.

Iwaizumi shook his head to clear his thoughts. He turned to look at Hanamaki pleadingly. The omega stepped back into the room and approached carefully. Iwaizumi could feel Oikawa tense and a low growl starting to develop in the alpha’s chest in spite of Hanamaki being an omega and thus not a direct threat.

Hanamaki crouched down next to the bench and Iwaizumi forced himself to keep eye contact with the omega. He leaned closer to smell the omega’s calming scent. Oikawa squeaked and tried to pull him back, but he now had more control of himself again and refused to budge.

“You don’t have to make any decisions that might change your relationship with someone,” Hanamaki said.

Iwaizumi heard Oikawa open his mouth to retort, and elbowed the alpha to keep him quiet.

“Iwa-chan!” Oikawa complained, and for the first time since he arrived Iwaizumi could feel his hold loosening.

Maybe the alpha was coming back to his senses after all, realising that he didn’t really want Iwaizumi. He had just wanted the omega, not Iwaizumi the person.

Surprisingly, it bothered him a lot. He had thought about Oikawa the alpha before, had wondered what would happen if his true nature was revealed and if their friendship could survive such a huge secret. He had wondered if he had feelings for Oikawa as an alpha and possible mate instead of just friendship. He had never bothered to take the time to think, because it was much easier to push those thoughts aside and think that “this isn’t the right moment.”

That is why he now found himself in this situation: uncertain as to what he should do, what he wanted to do, and what he wanted Oikawa to do.

To make matters worse, Iwaizumi felt a surge of slick and his heat started to seriously take over. He didn’t have much time to do anything. He needed to go home immediately.

Reluctantly (Oikawa’s pheromones smelled so sweet) Iwaizumi pried Oikawa’s arms off him and stood up, legs shaking slightly. Hanamaki stood up as well, placing a hand to Iwaizumi’s back to hold him steady. It was good. His scent made Iwaizumi feel more grounded when he turned to look at Oikawa, who was hanging his head in rejection.

Sometimes the right thing to do is to follow your heart, Iwaizumi thought to himself.

“Hey, Shittykawa,” he said, voice rough and slightly tired.

Oikawa lifted his head, eyes glistening under the fluorescent lights of the locker room, and Iwaizumi may have never seen such a beautiful sight before.

“You better take me home quickly,” he said.

It only took a fraction of a second for Oikawa to understand, perk up, and practically jump up from the bench.

“Are you sure?” Irihata asked, still clearly worried.

Iwaizumi’s head was starting to swim.

“I’ll bring your stuff over after practise,” Hanamaki whispered and stepped aside when Oikawa took his place next to Iwaizumi.

“I’m not sure it’s a good idea,” Mizoguchi offered. “Clearly you two haven’t talked about this before.”

Iwaizumi turned to look at both the coaches.

“I know what I’m doing,” he said, surprised by how certain he sounded.

He felt like his head was swaying, but he kept looking at the two men until Irihata nodded.

“Stay safe,” the alpha said and turned to push Mizoguchi out of the room.

Oikawa took a hold of Iwaizumi’s hand before they both turned to the door and left behind their coaches. Mizoguchi glanced at them nervously for one last time before they headed their separate ways.

After stepping through the school gates, Oikawa wrapped his arm around Iwaizumi’s waist. He smelled fierce, causing everyone to steer clear of them on their way to Iwaizumi’s. It felt strange to be protected by an alpha like that. Iwaizumi wasn’t used to not being able to stand up for himself.

However, it also felt reassuring to be pulled against the alpha’s body. Oikawa smelled safe and familiar, although Iwaizumi was now noticing his scent in a very different way from before when he was still under the influence of blockers. There was something domestic in it, and it made his heart swell with adoration.

A part of Iwaizumi was glad that his heat was taking up most of his brain functions so he was too distracted to really think about his feelings towards his childhood best friend.

“I’d kill to be a beta right now,” Iwaizumi mumbled.

Oikawa hummed in acknowledgement, but didn’t comment. It must have been weird to never have known that his best beta friend wasn’t a beta after all.

When they entered the house, it felt just like any other day, except Oikawa was holding Iwaizumi up now that the omega’s legs were even weaker. They made their way to his room where Oikawa had visited numerous times, and the only thing that made this time different was the strong smell of hormones in the air.

Oikawa helped Iwaizumi to the bed before letting go, much to Iwaizumi’s disappointment. His body had gotten so comfortable in the alpha’s hold that he now felt alone and cold sitting on the bed with Oikawa standing next to it.

“Iwa-chan,” Oikawa said. “Even if you regret this later, it’s not going to change our friendship.”

Iwaizumi laughed.

“That’s a lie,” he said.

Oikawa nodded in agreement. They both knew that if Oikawa was going to help Iwaizumi through his heat, it would have an irreversible effect on their relationship.

“Are you going to regret?” Iwaizumi asked.

He was struggling to hold onto the clarity in his head while heat was quickly taking over.

“Iwa-chan smells better than any other omega I have ever met,” Oikawa said thoughtfully. “I’ve always loved you as a friend. I don’t think mating with you would be a mistake.”

Iwaizumi nodded and closed his eyes to focus on what his head was telling him instead of his nature that was starting to scream for an alpha’s touch.

“Iwa-chan,” Oikawa called gently. “Should I leave?”

The air was thick with the alpha’s pheromones, and Iwaizumi’s body was reacting strongly. It had been a while since he had been off the blockers and gone into heat. His body was demanding his attention, but even more so the attention of the alpha standing before him. He thought about Oikawa’s strong body, how it was lean but so muscular, how it would feel against his own. He had seen Oikawa naked in the showers, he had seen how the alpha’s body developed after he had first presented, and he was very well aware of how being an alpha had affected his genitals. He wanted to see more, he wanted to see Oikawa hard and throbbing, and he wanted to feel it more than anything, wanted to feel the alpha push inside his tightness and tear him apart to make him feel good again.

“Iwa-chan!” Oikawa yelped and slapped his hands to both omega’s cheeks, not strong enough to hurt but enough to make him snap back to reality.

“It burns,” Iwaizumi said as Oikawa turned his head up to look at him.

“Iwa-chan, you need to focus just for a moment longer,” Oikawa said.

His fingers were burning against Iwaizumi’s skin, and he needed to feel more. No, he needed to think. He needed to know that this was what he would still want after his body was sated.

“You smell good,” he said instead.

Oikawa smiled with sadness in his eyes.

“Are you too far gone to decide?” the alpha asked.

He let go of Iwaizumi’s head and stepped back.

“I need to leave then,” he said.

“Oikawa,” Iwaizumi said quietly.

The alpha stopped and looked at him intensely. Iwaizumi was breathing hard. He had to get his thoughts in order over the next few seconds before he would succumb to his nature completely.

“You’re my best friend,” he said, struggling to keep his voice steady and not moan. “Who would make a better mate?”

Oikawa frowned in thought. His eyes were searching, and Iwaizumi hardly even noticed that he himself was starting to undress. His body was too hot. He couldn’t take it.

He forced himself to stop and look at Oikawa’s face once more.

“I’m sure,” he said and swallowed. “Tooru, I want you.”

That was all it took for Oikawa to climb over him and pull him into a searing kiss. The alpha’s lips were demanding but soft, and Iwaizumi wanted to drown into the touch. He felt like he was melting, his body turning soft under the alpha’s touch.

Oikawa pulled away way too fast, and Iwaizumi tried to chase him, but was pushed down.

“Iwa-chan,” Oikawa asked breathlessly. “Have you ever been with an alpha?”

Iwaizumi shook his head and moaned at the thought of an alpha spreading his hole open.

“How long since you last went to heat?” Oikawa asked.

Iwaizumi looked up and saw the alpha undressing over him. He moaned again, the sight enough to make his cock ache and drip pre-come on his underwear.

“Iwa-chan?” Oikawa asked and stopped.

Iwaizumi blinked.

“Since…” he started to say, but a wave of need hit him, shaking his body and causing him to curl into himself in pain. “Holidays…”

He didn’t know what Oikawa’s response for that was. His brain was only focused on the intensity of his heat, and he felt how wet his underwear was with slick, how wet his ass was with it too. He needed help, he needed it immediately, and…

And he was filled with calm when Oikawa pressed their bodies together and Iwaizumi’s nose was filled with his pheromones that carried a promise. He pressed his nose against the alpha’s scent gland and inhaled, distantly aware of how Oikawa was pulling his shorts off. Oikawa groaned into his ear when the smell of his musk filled the air as his clothes were removed. Iwaizumi whimpered in response, and cried out in pleasure when Oikawa’s cock brushed against his own.

“Iwa-chan?” he heard Oikawa call, but couldn’t immediately react, fingers pressing tightly into the alpha’s shoulders. “Iwa-chan? Are you okay? Did you just come?”

There were too many questions, and Iwaizumi wanted for Oikawa to shut up and fuck him instead of asking them. He opened his eyes that he didn’t remember closing, and looked up at the alpha who was looking down at him.

“Is it okay to go on?” Oikawa asked.

Iwaizumi nodded.

“Please,” he managed. “Alpha.”

Oikawa growled and spread Iwaizumi’s legs, exposing his glistening backside.

“You’re so wet, Iwa-chan,” he said in awe and glided a finger over the slick that had accumulated around the entrance. “Fuck, it smells so good.”

Without warning he pushed a finger past the tight ring of muscle, and Iwaizumi moaned, back arching and hips rolling to get more. Oikawa provided, finger moving in and out and curving to stroke over his walls.

“It’s so soft inside you, Iwa-chan,” Oikawa whispered.

His finger was making embarrassingly slick sounds, and if Iwaizumi’s face hadn’t already been on fire he would have blushed more than ever before.

“More,” he found himself pleading, and Oikawa pressed a second finger inside.

Iwaizumi cried out, thinking about how long and beautiful the alpha’s fingers were. The knowledge that there were two of those amazing digits inside him was quickly driving him mad.

A loud moan cut the air when Oikawa stroked against Iwaizumi’s prostate, causing the omega’s cock to jump against his belly. Oikawa chuckled happily and withdrew his fingers, much to Iwaizumi’s disappointment. The omega whined at the loss, even when Oikawa took a hold of his aching cock and gave it a stroke.

Iwaizumi looked up when Oikawa let go. The alpha was standing next to the bed, knees resting against the edge, and he lifted one leg to rest on the bed properly before spreading Iwaizumi’s legs better and pressing his hard cock against his wet entrance.

“Is it okay?” the alpha asked.

“Yes, god, please!” Iwaizumi replied loudly, uncaring of who might hear them.

Oikawa started pushing in slowly, his cock much bigger than anything that Iwaizumi had ever had inside himself. The stretch burnt, but not as badly as his heat.

“More,” Iwaizumi found himself chanting as Oikawa took his time to get the tip inside.

Oikawa had stopped listening to what he was saying, it seemed, as the alpha didn’t do anything to change what he was already doing. He was going in slow but steady, stopping every now and then to give the omega time to adjust. It was going well, until Iwaizumi screeched.

“Stop! Stop!” the omega yelled, trying to pull back.

Oikawa halted and took a hold of Iwaizumi’s wrists. It helped ground him, and Iwaizumi turned to look at Oikawa with teary eyes.

“Does it hurt?” Oikawa asked.

Iwaizumi nodded, unable to speak with how hard he was breathing.

“Shh, just relax,” Oikawa instructed, letting go of one hand to stroke Iwaizumi’s belly. “You’re doing great. Just relax.”

Iwaizumi sniffled but nodded, and it didn’t take long for the pain to start melting away. He tried to roll his hips to get more of Oikawa inside him, but the alpha took a firm hold of his hips to keep him still.

“Don’t,” Oikawa said. “I’ll go slow, okay?”

Iwaizumi nodded, and gently Oikawa rolled his hips. His cock wasn’t really moving inside Iwaizumi, the movement of the alpha’s hips only applying a bit of pressure against his entrance. Oikawa’s thrusts were smooth, and when his cock finally moved slightly, Iwaizumi moaned in pleasure, pain long forgotten.

The feeling of Oikawa’s cock moving against the tight opening of the omega was maddening, and Iwaizumi was tearing off the beddings while trying to deal with how good he was finally feeling. His head was thrashing around, and Oikawa shushed him gently while deepening his thrusts. Iwaizumi knew that the alpha was still holding back, and while he was extremely grateful, his body was also demanding more. He couldn’t quite decide which part to act on, so he ended up writhing incoherent words between moans.

Oikawa groaned and leaned forward to press his nose against Iwaizumi’s scent gland. After inhaling long, he licked over the gland, and Iwaizumi’s moan broke. The alpha continued to stimulate the spot with gentle nips, long licks and tiny kisses. Iwaizumi took a hold of Oikawa’s shoulders to not completely lose his touch to reality.

It seemed that Oikawa was also losing his self-control, as his hips were now driving inside the omega with more force instead of being mindful of any possible pain it might cause. However, Iwaizumi was in so much pleasure that his body was more accepting of the intrusion, and he hardly even realised when Oikawa bottomed out and their hips met. The sound of skin slapping against skin was completely new to Iwaizumi, and it added to the pleasure of being fucked out of his heat by an alpha. Oikawa’s grunts were echoing in his mind and he could feel the beginnings of a knot rub against his entrance.

Oikawa snaked a hand between their bodies to touch Iwaizumi’s throbbing erection. It was wet with his previous orgasm as well as pre-come that had been dripping down the shaft and onto his skin, and there were slick sounds in the air, something that sounded naughty and absolutely filthy, and Iwaizumi came with a small scream, almost unable to breathe as his body was shaken by his release.

Oikawa was rubbing their scent glands together, neck against neck, and it felt much more intimate than anything else they had done. Iwaizumi’s ass tightened around Oikawa’s cock, and it only took a few more thrusts of Oikawa’s hips before his knot caught onto the omega’s rim and locked them together, spurts of alpha semen painting Iwaizumi’s insides white. Oikawa was so deep, so deep, and Iwaizumi tried to pull him even deeper to feel everything, even the knot that was so big it was aching.

They both paused to breathe, Oikawa’s body resting over Iwaizumi’s. All was still, until the wildest beat of Iwaizumi’s heart had settled, and the reality started to dawn on him again.

Oikawa slowly rolled to the side and turned Iwaizumi with him. They faced each other properly for the first time since they had decided to go for it.

“How do you feel?” Oikawa asked.

“Full,” Iwaizumi replied.

Oikawa smirked.

“I feel okay,” Iwaizumi said. “I’m not regretting anything, if that’s what you wanted to know.”

Oikawa nodded and hummed almost absentmindedly.

“Iwa-chan,” he said slowly and looked into the omegas eyes. “We’re mates now.”

Iwaizumi felt his cheeks burn again. Oikawa’s eyes were such a deep shade of brown, how had he never noticed it before.

“We are,” he said quietly.

Oikawa smiled, and the way his hair was still looking as good as ever was infuriating. It made Iwaizumi’s heart skip a beat.

“I have to tell you something,” Oikawa said. “I was always quite disappointed that you were beta. I wanted you to be omega.”

Iwaizumi frowned.

“What does that mean?” he asked, trying to sound irritated, although he was way too sated to feel anything but soft drowsiness.

“It’s so much easier for an alpha to be with an omega than with a beta,” Oikawa said.

Iwaizumi looked at his face for a while.

“Are you trying to confess your feelings for me?” he then asked.

The alpha laughed happily.

“Iwa-chan always understands me!” he exclaimed and kissed the omega.

Oikawa’s lips were soft. They felt right. Iwaizumi closed his eyes and allowed himself to be swept away by love blooming inside him.

**Author's Note:**

> I've been working on some long fics and wrote this on the side.
> 
> Also I want to say that I'm very appreciative of all the support I get from you as comments and kudos! Knowing that people enjoy what I write is what keeps me going!
> 
> I have [a dedicated writing blog](http://mean-whalewrites.tumblr.com) but also sometimes talk about writing [on twitter](http://twitter.com/mean_whale), but to follow me on twitter please be over 18!


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